/***************************************************************************
 *   Copyright (c) Konstantinos Poulios      (logari81@gmail.com) 2011     *
 *                                                                         *
 *   This file is part of the FreeCAD CAx development system.              *
 *                                                                         *
 *   This library is free software; you can redistribute it and/or         *
 *   modify it under the terms of the GNU Library General Public           *
 *   License as published by the Free Software Foundation; either          *
 *   version 2 of the License, or (at your option) any later version.      *
 *                                                                         *
 *   This library  is distributed in the hope that it will be useful,      *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU Library General Public License for more details.                  *
 *                                                                         *
 *   You should have received a copy of the GNU Library General Public     *
 *   License along with this library; see the file COPYING.LIB. If not,    *
 *   write to the Free Software Foundation, Inc., 59 Temple Place,         *
 *   Suite 330, Boston, MA  02111-1307, USA                                *
 *                                                                         *
 ***************************************************************************/

#include <iostream>
#include <iterator>
#include "SubSystem.h"

namespace GCS
{

// SubSystem
SubSystem::SubSystem(std::vector<Constraint *> &clist_, VEC_pD &params)
: clist(clist_)
{
    MAP_pD_pD dummymap;
    initialize(params, dummymap);
}

SubSystem::SubSystem(std::vector<Constraint *> &clist_, VEC_pD &params,
                     MAP_pD_pD &reductionmap)
: clist(clist_)
{
    initialize(params, reductionmap);
}

SubSystem::~SubSystem()
{
}

void SubSystem::initialize(VEC_pD &params, MAP_pD_pD &reductionmap)
{
    csize = clist.size();

    // tmpplist will contain the subset of parameters from params that are
    // relevant for the constraints listed in clist
    VEC_pD tmpplist;
    {
        SET_pD s1(params.begin(), params.end());
        SET_pD s2;
        for (std::vector<Constraint *>::iterator constr=clist.begin();
             constr != clist.end(); ++constr) {
            (*constr)->revertParams(); // ensure that the constraint points to the original parameters
            VEC_pD constr_params = (*constr)->params();
            s2.insert(constr_params.begin(), constr_params.end());
        }
        std::set_intersection(s1.begin(), s1.end(), s2.begin(), s2.end(),
                              std::back_inserter(tmpplist) );
    }

    plist.clear();
    MAP_pD_I rindex;
    if (reductionmap.size() > 0) {
        int i=0;
        MAP_pD_I pindex;
        for (VEC_pD::const_iterator itt=tmpplist.begin();
             itt != tmpplist.end(); itt++) {
            MAP_pD_pD::const_iterator itr = reductionmap.find(*itt);
            if (itr != reductionmap.end()) {
                MAP_pD_I::const_iterator itp = pindex.find(itr->second);
                if (itp == pindex.end()) { // the reduction target is not in plist yet, so add it now
                    plist.push_back(itr->second);
                    rindex[itr->first] = i;
                    pindex[itr->second] = i;
                    i++;
                }
                else // the reduction target is already in plist, just inform rindex
                    rindex[itr->first] = itp->second;
            }
            else if (pindex.find(*itt) == pindex.end()) { // not in plist yet, so add it now
                plist.push_back(*itt);
                pindex[*itt] = i;
                i++;
            }
        }
    }
    else
        plist = tmpplist;

    psize = plist.size();
    pvals.resize(psize);
    pmap.clear();
    for (int j=0; j < psize; j++) {
        pmap[plist[j]] = &pvals[j];
        pvals[j] = *plist[j];
    }
    for (MAP_pD_I::const_iterator itr=rindex.begin(); itr != rindex.end(); ++itr)
        pmap[itr->first] = &pvals[itr->second];

    c2p.clear();
    p2c.clear();
    for (std::vector<Constraint *>::iterator constr=clist.begin();
         constr != clist.end(); ++constr) {
        (*constr)->revertParams(); // ensure that the constraint points to the original parameters
        VEC_pD constr_params_orig = (*constr)->params();
        SET_pD constr_params;
        for (VEC_pD::const_iterator p=constr_params_orig.begin();
             p != constr_params_orig.end(); ++p) {
            MAP_pD_pD::const_iterator pmapfind = pmap.find(*p);
            if (pmapfind != pmap.end())
                constr_params.insert(pmapfind->second);
        }
        for (SET_pD::const_iterator p=constr_params.begin();
             p != constr_params.end(); ++p) {
//            jacobi.set(*constr, *p, 0.);
            c2p[*constr].push_back(*p);
            p2c[*p].push_back(*constr);
        }
//        (*constr)->redirectParams(pmap); // redirect parameters to pvec
    }
}

void SubSystem::redirectParams()
{
    // copying values to pvals
    for (MAP_pD_pD::const_iterator p=pmap.begin();
         p != pmap.end(); ++p)
        *(p->second) = *(p->first);

    // redirect constraints to point to pvals
    for (std::vector<Constraint *>::iterator constr=clist.begin();
         constr != clist.end(); ++constr) {
        (*constr)->revertParams();  // this line will normally not be necessary
        (*constr)->redirectParams(pmap);
    }
}

void SubSystem::revertParams()
{
    for (std::vector<Constraint *>::iterator constr=clist.begin();
         constr != clist.end(); ++constr)
        (*constr)->revertParams();
}

void SubSystem::getParamMap(MAP_pD_pD &pmapOut)
{
    pmapOut = pmap;
}

void SubSystem::getParamList(VEC_pD &plistOut)
{
    plistOut = plist;
}

void SubSystem::getParams(VEC_pD &params, Eigen::VectorXd &xOut)
{
    if (xOut.size() != int(params.size()))
        xOut.setZero(params.size());

    for (int j=0; j < int(params.size()); j++) {
        MAP_pD_pD::const_iterator
          pmapfind = pmap.find(params[j]);
        if (pmapfind != pmap.end())
            xOut[j] = *(pmapfind->second);
    }
}

void SubSystem::getParams(Eigen::VectorXd &xOut)
{
    if (xOut.size() != psize)
        xOut.setZero(psize);

    for (int i=0; i < psize; i++)
        xOut[i] = pvals[i];
}

void SubSystem::setParams(VEC_pD &params, Eigen::VectorXd &xIn)
{
    assert(xIn.size() == int(params.size()));
    for (int j=0; j < int(params.size()); j++) {
        MAP_pD_pD::const_iterator
          pmapfind = pmap.find(params[j]);
        if (pmapfind != pmap.end())
            *(pmapfind->second) = xIn[j];
    }
}

void SubSystem::setParams(Eigen::VectorXd &xIn)
{
    assert(xIn.size() == psize);
    for (int i=0; i < psize; i++)
        pvals[i] = xIn[i];
}

double SubSystem::error()
{
    double err = 0.;
    for (std::vector<Constraint *>::const_iterator constr=clist.begin();
         constr != clist.end(); ++constr) {
        double tmp = (*constr)->error();
        err += tmp*tmp;
    }
    err *= 0.5;
    return err;
}

void SubSystem::calcResidual(Eigen::VectorXd &r)
{
    assert(r.size() == csize);

    int i=0;
    for (std::vector<Constraint *>::const_iterator constr=clist.begin();
         constr != clist.end(); ++constr, i++) {
        r[i] = (*constr)->error();
    }
}

void SubSystem::calcResidual(Eigen::VectorXd &r, double &err)
{
    assert(r.size() == csize);

    int i=0;
    err = 0.;
    for (std::vector<Constraint *>::const_iterator constr=clist.begin();
         constr != clist.end(); ++constr, i++) {
        r[i] = (*constr)->error();
        err += r[i]*r[i];
    }
    err *= 0.5;
}

/*
void SubSystem::calcJacobi()
{
    assert(grad.size() != xsize);

    for (MAP_pD_pD::const_iterator param=pmap.begin();
         param != pmap.end(); ++param) {
        // assert(p2c.find(param->second) != p2c.end());
        std::vector<Constraint *> constrs=p2c[param->second];
        for (std::vector<Constraint *>::const_iterator constr = constrs.begin();
             constr != constrs.end(); ++constr)
            jacobi.set(*constr,param->second,(*constr)->grad(param->second));
    }
}
*/

void SubSystem::calcJacobi(VEC_pD &params, Eigen::MatrixXd &jacobi)
{
    jacobi.setZero(csize, params.size());
    for (int j=0; j < int(params.size()); j++) {
        MAP_pD_pD::const_iterator
          pmapfind = pmap.find(params[j]);
        if (pmapfind != pmap.end())
            for (int i=0; i < csize; i++)
                jacobi(i,j) = clist[i]->grad(pmapfind->second);
    }
}

void SubSystem::calcJacobi(Eigen::MatrixXd &jacobi)
{
    calcJacobi(plist, jacobi);
}

void SubSystem::calcGrad(VEC_pD &params, Eigen::VectorXd &grad)
{
    assert(grad.size() == int(params.size()));

    grad.setZero();
    for (int j=0; j < int(params.size()); j++) {
        MAP_pD_pD::const_iterator
          pmapfind = pmap.find(params[j]);
        if (pmapfind != pmap.end()) {
            // assert(p2c.find(pmapfind->second) != p2c.end());
            std::vector<Constraint *> constrs=p2c[pmapfind->second];
            for (std::vector<Constraint *>::const_iterator constr = constrs.begin();
                 constr != constrs.end(); ++constr)
                grad[j] += (*constr)->error() * (*constr)->grad(pmapfind->second);
        }
    }
}

void SubSystem::calcGrad(Eigen::VectorXd &grad)
{
    calcGrad(plist, grad);
}

double SubSystem::maxStep(VEC_pD &params, Eigen::VectorXd &xdir)
{
    assert(xdir.size() == int(params.size()));

    MAP_pD_D dir;
    for (int j=0; j < int(params.size()); j++) {
        MAP_pD_pD::const_iterator pmapfind = pmap.find(params[j]);
        if (pmapfind != pmap.end())
            dir[pmapfind->second] = xdir[j];
    }

    double alpha=1e10;
    for (std::vector<Constraint *>::iterator constr=clist.begin();
         constr != clist.end(); ++constr)
        alpha = (*constr)->maxStep(dir, alpha);

    return alpha;
}

double SubSystem::maxStep(Eigen::VectorXd &xdir)
{
    return maxStep(plist, xdir);
}

void SubSystem::applySolution()
{
    for (MAP_pD_pD::const_iterator it=pmap.begin();
         it != pmap.end(); ++it)
        *(it->first) = *(it->second);
}

void SubSystem::analyse(Eigen::MatrixXd &J, Eigen::MatrixXd &ker, Eigen::MatrixXd &img)
{
}

void SubSystem::report()
{
}

void SubSystem::printResidual()
{
    Eigen::VectorXd r(csize);
    int i=0;
    double err = 0.;
    for (std::vector<Constraint *>::const_iterator constr=clist.begin();
         constr != clist.end(); ++constr, i++) {
        r[i] = (*constr)->error();
        err += r[i]*r[i];
    }
    err *= 0.5;
    std::cout << "Residual r = " << r.transpose() << std::endl;
    std::cout << "Residual err = " << err << std::endl;
}


} //namespace GCS
